Wheels
Several years ago, my bicycle was stolen. Thinking I had done my best to keep it secure from the thieves of the world, I was at a loss and decided against replacing it with more bait.
After much talk and not much action, I have finally replaced that bike. Last week, I purchased a Jamis 2007 Commuter 3.0 - quite a mouthful. Being a technical type, of course I was obliged to research every aspect of each bike that fit my criteria: internally geared, 700c wheels, aluminum frame and mounts for a rack and fenders. Now that I have made the buy, I would like to present the numbers and my reasoning.
Purpose
My reason for finally replacing my lost bike is one of circumstance. I now live close enough to my employer to commute to work (~6km) and most of the places I frequent otherwise are within about that same radius.
The style of bike best suited to around-town recreation and commuting is called a hybrid - being a hybrid between road and mountain bike styles.
Gears
There are two basic gear types on a modern road bike, internal and derailleur. There are, as with everything, trade-offs to be made between the two. The aforelinked wiki articles explain that better than I could, but my principle concerns were maintenance and ease-of-use. Internal gears require both vastly less maintenance than derailleurs, but also allow shifting while stopped and keep the chain in the most efficient alignment.
The Jamis uses a Shimano Nexus Inter-8 hub with 700 x 32c wheels, 170mm crank and a 36 tooth sprocket. This hub has a very respectable 306% overall gear ratio and in this bike's configuration it provides a solid 16.6 gear-inches in the first gear - plenty low for most of the hills in the area I plan to ride.
As you can see, the gears are fairly evenly spaced over the available gear-inches:
However, the inter-gear ratios are a bit sporadic. A better hub, such as the top-of-the-line Rohloff Speedhub, would provide not only a wider overall gear ratio, but a smoother curve, here:
Of course, I could upgrade the hub or sprocket in the future, should I find this geometry limiting.
Wheels
The knobby tires of a mountain bike increase the amount of air resistance a bicyclist works against and really are not designed for around-town riding. It is important to me to have a lightweight, robust wheel that suits the area I am riding in. The best choice here is the 700c rim of a road bike; the Jamis uses a 700 x 32c, 622mm wheel that fits my need perfectly.
Frame
Frames in my price range are made from steel alloy and aluminum. Steel is easily repaired with a simple welder if it cracks, but aluminum offers light weight and no rust. The weight is particularly important to me - with a rack and pannier full of groceries, the weight of a steel frame will be noticeable.
Accessories
Not all bikes come with the tabs for fenders and racks from the factory. A shame, in my opinion. Fenders not only have an attractive, classic look, but also reduce the amount of mud and water the wheels spray back on the chain and gears. This is less of an issue with internal gears, but important for chain-life nonetheless.
I plan to use this bike as more than just a commuter. I live a short distance from groceries, clothing stores and restaurants that I would rather bike to than drive. With a rack and pannier, I can easily accommodate any small purchases (or leftovers!) I may find.
The Shop
Finally, I would like to say that my LBS - Bicycle Bananas - was helpful, courteous and had an extremely competitive price for the Jamis. What's more, the new bike comes with a year of free maintenance, a free water bottle and holder and 10% off accessories for the next year. A great deal all around!